1. Field of the Invention
The present invention relates to an optical disk, a recording method and data recording apparatus for recording data on this optical disk, and a data reproducing method and data reproducing apparatus for reproducing data from the optical disk. More particularly, an optical disk on which a detection signal for permitting the detection of a tilt amount is recorded, a recording method and data recording apparatus for recording data together with a tilt amount detection signal on this optical disk, and a data reproducing method and data reproducing apparatus for detecting the tilt amount detection signal from the optical disk to reproduce data therefrom.
This invention also relates to an optical disk having an evaluation test pattern, a recording method and data recording apparatus for recording reproduction data together with evaluation test data on this optical disk, and a method and apparatus for reading evaluation data from the optical disk to evaluate the optical disk. More particularly, this invention relates to an optical disk on which an evaluation test pattern, for determining whether or not a manufactured optical disk is defective, is recorded, a recording method and recording apparatus for recording reproduction data together with an evaluation test pattern on this optical disk, and a method and apparatus for detecting an evaluation test pattern signal from the optical disk to determine if the optical disk is defective.
2. Description of the Related Art
With regard to optical disk apparatuses, as one type of information recording and reproducing apparatus, which optically reproduce information, it is known that the greater the relative tilt amount between the disk reproducing surface and the surface of an objective lens becomes, the more the frequency characteristic of reproduced signals is deteriorated so that the error rate at the time of reading data becomes impaired. This relative tilt amount is determined by the tilt caused by the physical deformation of a disk and the tilt caused by the physical inclination of the objective lens of an optical head.
To overcome such a problem, there is a conventional method of mechanically tilting the optical head to cancel the relative tilt of the disk reproducing surface and the surface of the objective lens as disclosed in, for example, Jpn. Pat. Appln. KOKAI Publication No. 3-142723. This conventional apparatus has an optical pickup supported in a tiltable manner and mechanically coupled to a motor as a tilting source via a gear. This apparatus detects the tilt amount of an optical disk and drives the motor according to the tilt amount to incline the optical pickup via the gear, so that the relative tilt amount between the objective lens and the optical disk is controlled. Such a control system is considered sufficient to cancel the relative tilt between the disk's reproducing surface and the surface of the objective lens.
Because an apparatus which employs such a conventional control system has mechanical components, such as the motor and gear in the control system, tilt compensation control in a high band is difficult and tilt cannot be compensated in bands other than the control band in the vicinity of the DC component range. Further, the use of the mechanical components makes it difficult to design the apparatus compact. As optical disks capable of recording a vast amount of information at higher density are being developed today, particularly, the tilt compensation in the DC component range alone becomes insufficient, and people are demanding a system which can accurately accomplish tilt compensation in a high band as well as in the DC component range.
For optical disk apparatuses, as one type of information recording and reproducing apparatus, which optically reproduce data, it is premised that data should be recorded at high precision on an optical disk in order to reproduce data at high accuracy. If the forming precision of pits formed on an optical disk is poor, for example, signals would not be reproduced at a high precision or at a low error rate so that data reproduction may become disabled. It is also known that if the frequency characteristics of reproduced signals becomes poor, the error rate at the time of reading data becomes impaired while if there is a significant crosstalk component from adjoining rows of pits, retrieval data cannot be acquired from a target row of pits.
While there has been a demand for the system which determine at high precision if manufactured optical disks are defective, it is considered sufficient for the actual reproduction system to check recorded data on an optical disk which does not have a relatively large storage capacity in order to determine whether or not data recording is satisfactory. As optical disks capable of recording a vast amount of and high-density information are being developed today, however, people demand a system which can determine at high precision if data recording has failed.